Đáp án:
a) x=5
b) \(x = \dfrac{7}{3}\)
c) x=1
Giải thích các bước giải:
\(\begin{array}{l}
a)DK:x \ge 1\\
\dfrac{3}{4}.2\sqrt {x - 1} - 4\sqrt {x - 1} = - 5\\
\to \dfrac{3}{2}\sqrt {x - 1} - 4\sqrt {x - 1} = - 5\\
\to - \dfrac{5}{2}\sqrt {x - 1} = - 5\\
\to \sqrt {x - 1} = 2\\
\to x - 1 = 4\\
\to x = 5\\
b)DK:x > 2\\
\sqrt {\dfrac{3}{{x - 2}}} = 3\\
\to \dfrac{3}{{x - 2}} = 9\\
\to 9x - 18 = 3\\
\to 9x = 21\\
\to x = \dfrac{7}{3}\\
c)DK:x \ge 0\\
3x + \sqrt x - 4 = 0\\
\to \left( {\sqrt x - 1} \right)\left( {3\sqrt x + 4} \right) = 0\\
\to \sqrt x = 1\left( {do:3\sqrt x + 4 > 0\forall x \ge 0} \right)\\
\to x = 1
\end{array}\)
